Metadata:
Identification_Information:
Citation:
Citation_Information:
Originator: Roger Tankersley, Jr.
Publication_Date: 1998
Title: roads
Edition: 1
Geospatial_Data_Presentation_Form: Map
Publication_Information:
Publication_Place: Norris TN
Publisher: Tennessee Valley Authority
Description:
Abstract:
This map is an ARC/INFO coverage of all roads in the mid-Atlantic region. Class 1-4 roads (the ones included here) include major highways to unimproved roads.
Purpose:
These data were created as part of a regional assessment of landscape conditions
in the mid-Atlantic region (SFR 3) (Jones et al., 1997).
Time_Period_of_Content:1995
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date:
Ending_Date:
Currentness_Reference: None
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -84 degrees West
East_Bounding_Coordinate: -74 degrees West
North_Bounding_Coordinate: 43 degrees North
South_Bounding_Coordinate: 36 degrees North
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword:Roads
Theme_Keyword:
Theme_Keyword:
Theme_Keyword:
Theme_Keyword:
Theme_Keyword:
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: United States
Place_Keyword: Standard Federal Region III
Access_Constraints: None
Use_Constraints: None
Point_of_Contact:
Contact_Information:
Contact_Person_Primary: Bruce Jones
Contact_Person:
Contact_Organization: EPA Landscape Ecology Division
Contact_Address:
Address_Type: mailing and physical address
Address: U.S. Environmental Protection Agency, Box 93478
City: Las Vegas
State_or_Province: Nevada
Postal_Code: 89193-3478
Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov
Data_Set_Credit: USGS RF3 data.
Native_Data_Set_Environment:
These data are presently stored in ARC/INFO format.
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report: none
Logical_Consistency_Report: none
Completeness_Report: Complete
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: None
Source_Information:
Source_Citation:
Citation_Information:
Other_Citation_Details: Jones, K.B., Riitters, K.H., Wickham, J.D., Tankersley, R.D.,
O'Neill, R.V., Chaloud, D.J., Smith, E.R., and Neale, A.C. 1997. An Ecological
Assessment of the United States Mid-Atlantic Region: A Landscape Atlas.
EPA/600/R97/130, U.S. Environmental Protection Agency, Office of Research
and Development, Washington, DC.
Source_Information:
Source_Citation:
Citation_Information:
Other_Citation_Details:
Process_Step:
Process Description:
The RF3 file is based upon the USGS 1:100,000 scale
hydrography DLGs. The data were acquired by EPA-OW on
240 tapes which contained 54,000 files. The first
processing performed was to convert from UTM to
latitude/longitude. This conversion was accomplished
preserving the nearest 1/10,000 of a degree, which is
well within the stated resolution of these data. The
data were then collapsed into line records (trace files)
without nodes, and the line records were concatenated.
There were then 4 million line elements and 93 million
latitude/longitude coordinates. Each line, or trace,
retained a key record that can be directed back to the
original DLG data tape if necessary.
Traces were then assigned to USGS Cataloging Units (CU).
Traces that crossed CU boundaries were assigned to both
CUs. A CU is a geographic area representing all or part
of a surface drainage basin, a combination of basins, or
a distinct hydrologic feature. There are approximately
2150 CUs in the Nation. The USGS CU boundaries were
developed at a scale of 1:2,000,000 (see Figure 1).
They represent the "smallest element in the hierarchy of
hydrologic units" (U.S. Geological Survey, 1982). CUs
are not accurately correlated to topography and do not
always correspond directly to true watersheds as they
are more administrative in function.
Horizon Systems Corporation, the prime contractor to
EPA-OW, developed a software tool called PC Reach File
(PCRF). PCRF is the program that performs the RF3 file
construction. Production development of RF3 proceeds in
discrete units corresponding to the CU. Because of the
ability to run many of the steps in batch, a given analyst
running PCRF may be working on as many as 25 CUs at a time.
Building The RF3 Network.
In order to update the RF2 file to RF3, the RF2 data,
the DLG data and the CU boundaries are all downloaded to
a PC running PCRF. There, an analyst identifies a
starting point for the automated construction of the
network topology. The starting point designated was the
furthest reach downstream and the network was built up
in the reverse direction of flow. Between reaches there
may be gaps, usually along map sheet boundaries.
Therefore, a search tolerance of 3/10,0000 of a degree
or approximately 100 feet was specified in order to
"bridge" these gaps. Edgematching takes place by the
addition of segments in these gaps. Once this has been
completed, the analyst will "replay" and supervise the
network that was created. There may be some network
discrepancies that are not able to be resolved by PCRF
and that may cause a break in the processing. These are
resolved by the analyst.
Once the network is built, segment and milepoint numbers
must be assigned along the network. The analyst begins
this session by viewing both the RF2 and the processed
DLG data together, color coded for differentiation. The
analyst then will "tag" the RF2 segment endpoints to the
corresponding DLG points. PCRF will then work upstream
from the downstream end of the segment and allocate
milepoints. The RF2 milepoints are retained in RF3,
despite the actual length of the new segments. In other
words, the milepoint figures will not reflect the true
length of the RF3 reaches. For example, if an RF2
segment had ten reaches (differentiated by milepoints),
the more detailed RF3 segment will also have ten
milepoints, but the trace of these reaches will be
entirely different. New milepoints are not being
created because this would disrupt databases that index
to the earlier Reach Files. The actual length of
reaches as derived from the DLG trace is recorded in a
field called SEGL. New segments and reaches are not an
uncommon outcome of this conversion to the more highly
resolved hydrography network. In this step, PCRF will
assign new SEG/MI numbers to traces that appear in the
1:100,000 DLG that did not exist in the previous
1:500,000 Trace File.
Source_Used_Citation_Abbreviation:
Source_Produced_Citation_Abbreviation:
Process_Date:
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: vector
Raster_Object_Information:
Raster_Object_Type:
Row_Count:
Column_Count:
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition: Planar:
Map_Projection:
Map_Projection_Name: Lambert_Azimuthal
Lambert_Azimuthal:
Radius of Sphere of Reference: 6370997
Longitude_of_Central_Meridian: -100 0 0
Latitude_of_Projection_Origin: 45 0 0
False_Easting: 0.0
False_Northing: 0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: Row and column
Coordinate_Representation:
Abscissa_Resolution:
Ordinate_Resolution:
Planar_Distance_Units: meters
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label:
Entity_Type_Definition:
Entity_Type_Definition_Source: ARC/INFO
Attribute:
Attribute_Label: ORDER
Attribute_Definition: Stream order, ranging from 1st-7th.
Attribute_Definition_Source: ARC/INFO
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Maximum:
Range_Domain_Minimum:
Attribute_Measurement_Frequency: None planned
Attribute:
Attribute_Label: CODE
Attribute_Definition: RF3 Reach Type Code.
Attribute_Definition_Source: ARC/INFO
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Maximum:
Range_Domain_Minimum:
Attribute_Measurement_Frequency: None planned
Overview_Description:
Entity_and_Attribute_Overview:
Entity_and_Attribute_Detail_Citation: Not available
Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Bruce Jones
Contact_Organization: EPA Landscape Ecology Division
Contact_Address:
Address_Type:
Address: U.S. Environmental Protection Agency, Box 93478
City: Las Vegas
State_or_Province: Nevada
Postal_Code: 89193-3478
Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov
Metadata_Reference_Information:
Metadata_Date: 19980901
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Roger Tankersley, Jr.
Contact_Organization: University of Tennessee, Department of Geography
Contact_Address:
Address_Type:
Address: 428 G&G Building
Address:
City: Knoxville
State_or_Province: TN
Postal_Code: 37996
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: 19940608
Metadata_Security_Information:
Metadata_Security_Classification_System: None
Metadata_Security_Classification: Unclassified
Metadata_Security_Handling_Description: None